We have a contract to build an ice skating rink. The rink slab will be 80 by 180 ft (24 by 55 m) and 5 in. (125 mm) thick. The project specification requires 4000 psi (28 MPa) concrete, and the drawings show No. 4 bars at 12 in. (300 mm) on center each direction for bottom reinforcing and “6x6x10 WWM” for top reinforcing. Coolant pipes (1 in. [25 mm] HDPE) are shown at slab mid-depth. No sawed joints are shown in the slab, but there is an expansion joint around the perimeter. With such a large slab and no contraction joints, won’t cracking be likely? What should we tell the Owner to expect? How can we minimize cracking?